Cathode ray tube apparatus



March 24, 1964 FRENKEL CATHODE RAY TUBE APPARATUS Filed March 6, 1957 Zorrumdmm I N VE N TOR orf/4Q FQMA/H BY Tommy United States Patent M of Delaware Filed Mar. 6, 1957, Ser. No. 644,330 5 Claims. (Cl. 313-86) This invention relates generally to cathode ray tube ,apparatus and more particularly, to a variety of cathode ray tube wherein an electron beam is shaped into predetermined configurations for presentation of intelligible information upon the target or screen of the tube.

In `a shaped beam tube, many problems are encountered in the shaping `of the electron beam and displaying the -shaped beam cross section upon a screen of the tube. Copending applications of McNaney et al., Serial No. 507,856, iiled May l2, 1955, now Patent 2,824,250, and Hamann, Serial No. 507,902, filed May 12, 1955, now abandoned, both of which are assigned to the common assignee hereof, the tube exemplified utilizes a matrix or beam shaping member to effect the actual shaping of the electron beam. It is necessary that the electron beam be deflected by selection deflection means to illuminate desired areas upon the beam shaping member. As this is done, the beam may be directed away from the `general longitudinal axis of the tube on a path diverging from the axis. It is necessary to redirect or converge the beam with the axis. A convergence means effects the necessary redirection of the electron beam from its divergent path to the path convergent with the axis of the tube. The convergence means supplied not only performs the function of redirecting the electron beam from a divergent to a convergent path with the axis of the tube, but substantially simultaneously effects focusing and imaging of the beam cross section. The convergence means is designed with certain relatively fixed imaging chanacteristics, i.e., the object to image distance is fixed. Therefore, lto obtain optimum focusing conditions the matrix or beam shaping member is so positioned as to permit imaging of its openings or `object by the convergence means at the screen.

As shown in copending applications, following the action of the convergence means, the electron beam may then be deflected back to the axis by reference or compensation deflection means. The beam is then directed toward the screen generally `along the axis and may be nally deflected by final deflection means7 such as, an electromagnetic yoke or electrostatic deflection plates. As noted, the electro-optical characteristics of the convergence means determines the positioning as well as the electro-optical characteristics `of the aforementioned components, and is generally designed to effect imaging at the screen. Design of the convergence means to effect imaging of the matrix openings 'at the screen is xed and changing the image point or the size of the screen display normally requires changing the physical characteristics of the convergence means. As at certain times in the utilization of shaped beam tubes, it becomes desirable to vary the sizeof the image upon the screen, this formerly had to be accomplished by redesigning and building a new convergence means usually also la new tube.

The instant invention overcomes the aforestated inadequacy and accomplishes desired post acceleration of the shaped beam by establishing independently of the convergence means, any desired set of focus conditions upon the beam for the changes imaging land size relationsY of the matrix openings upon the screen. The inclusion `of the additional focusing lens permits independent operation upon the shaped beam imaging the cross section and changing its size when and where desired.

In addition to the aforestated objects and advantages,

3,126,494 Patented Mar. 24, 1964 ICC it is an object of the present invention to provide in a shaped beam tube `an electro-optical system capable of displaying varying sized characters imaged at desired screen positions.

It is another object of the present invention to provide a simple and trouble-free construction in a shaped beam tube which permits variation of the planes of imaging and the cross sectional size of the shaped electron beam independently of the main tube optics.

It is another object of the present invention to provide a shaped beam tube in which considerable flexibility exists in the object to image ratio of the finally displayed character.

It is 4another object of the present invention to provide an electron optical construction which permits desired variation in the mechanical characteristics of the tube envelope, namely, shortening it if so desired.

IIt is another object of the present invention to pro-V vide a shaped beam tube wherein the major optics are independent of the length of the longitudinal axis of the tube.

Objects and advantages other than those set forth above will be apparent when read in connection with the specication and accompanying drawings, in which:

The .single ligure is ya cross sectional schematic of a shaped beam tube embodying the invention.

Shown in the ligure is a shaped beam tube having an evacuated envelope 10. Positioned therein and at one end of the envelope 1li, is beam generating and projecting means 11 capable of and projecting an electron beam 16 'along substantially a longitudinal axis 12 of tube 10'. A conventional electron generating cathode 13 along with desired accelerating and focusing anodes 14 may be included in the beam generating means 11. A target 1'5, such as la phosphor screen, may be positioned at the other end of the tube 119 for electron-to-light conversion of the information to be displayed by a shaped electron beam 17.

The electron beam |16 may be shaped into predetermined character cross sections or configurations by a beam shaping member 18 positioned along the axis intermediate target 15 and beam generating means 11 resulting in the shaped electron beam 17. Shaped electron beam 17 acquires the cross sectional shape imparted to beam `16 by stencil-like openings or objects in beam shaping member 18. A selection deflection means 19, which may be `of electromagnetic or electrostatic construction, is shown in the exempliiication as two pairs of electrostatic deilection plates placed in quadrature with each other. The selection deection means 19 is capable of effecting desired beam 1d positioning upon the beam shaping member 18. Except when the electron beam 16 illuminates the character, object, opening or portion of the beam shaping member '18 upon the laxis, the selection deflection means 19 effects deflection of beam 16 in la direction away from the axis 12 or stated another way, on a ydivergent path from the axis.

Convergence means Ztl, which may be of an electromagnetic or electrostatic construction, is shown in the instant exemplilication as electromagnetic, and is utilized to effect a converging of the divergent electron beam 16. Along with its convergence, convergence means 20 effects substantially simultaneously, a focusing action of the cross section of shaped beam 17 whereby the character illuminated in the beam shaping member 18 is imaged at a desired imaging point usually at the target 15. It is this imaging or focusing characteristic of the particular convergence means 20 to effect imaging of the matrix upon the screen. Under the normal application, the convergence means simultaneously must image the selection deflection means 19 upon the referencing deflection means 23. Therefore, there is considerable necessity for correlating all of the desired characteristics into the predetermined design of the convergence means 2), leaving little latitude for any subsequent changes or compromises, i.e., the image points and the character sizes are predetermined.

Convergence means 26, therefore, effects a redirection of the divergence shaped electron beam 17 and present the beam 17 on a path converging with the axis to referencing deflection means 23. Beam 17 is returned substantially coaxially with and along axis 12 by reference deflection means 23.

The shaped beam then being on axis enters an electron focusing lens 25, which preferably, is independently controllable and, therefore, permits independent imaging of the cross section of the electron beam from that of convergence means 20. This, of course, also permits variation in the point of imaging as well as the size of the image independently of that established by the characteristics of the convergence means 20. Electron focusing lens 25 may utilize any known type of electrostatic lens system, such as, a .7a-element Einzel lens or a 2 or 3-element accelerating type lens, first of which, are well known in the art. The present exemplification utilizes a 3-element accelerating type lens 25. Electrostatic lensing is utilized and preferred over electromagnetic in that power requirements are minimal and the field generated is capable of being adequately controlled free of interference with adjoining fields. Application of independent voltages to the lenses, and varying these voltages will permit independent imaging and changing of cross sectional size of the beam 17, therefore, making the entire electro-optical system independent of the fixed characteristics of the convergence means 20. The electron lens 25, therefore, permits considerable latitude in changing the previously fixed object to image distance of the convergence means 20 without interference with adjacent established electromagnetic and electrostatic fields. Electron lens 25 permits construction of an overall shaped beam tube which has a length substantially less than the object to image distance of the convergence means 20, if it be so desired. Utilization of electron lens 25 also permits additional acceleration to be imparted to the shaped beam 17 thereby increasing the brightness of the display.

For example, it has been noted in experimentation, that with the utilization of the electrostatic electron leus 25, and utilizing its post shaping acceleration capability, that it is possible to display 20% smaller characters at the screen for a 40% increase in beam acceleration through the lens. To display the same information density as previously displayed by apparatus such as the aforementioned applications of McNaney et al. and Hamann, the screen size may, with the new improvement, be reduced by 20% and, therefore, permitting attendant reduction in current of the final deflection means 28.

The various circuitry symbolized by block diagram representation in FIGURE l actuated by a source of control signals may be utilized to effect operation of tube 10. As aforestated, it is desired to have a focus control unit that is capable of operations independently of a convergence control unit. The focus control unit may supply a high voltage capable of being varied as desired.

A particular embodiment of the invention illustrated and described herein is illustrative only, and the invention includes such other modifications and equivalents as may readily appear to those skilled in the art within the scope of the appended claims.

I claim:

l. In a shaped beam tube including beam generating and projecting means at one end thereof for projecting an electron beam along a tube axis, and a target responsive to said beam at the other end thereof, a beam shaping member positioned along the axis intermediate the target and the beam generating means for selectively shaping the electron beam, a selection deflection means positioned intermediate the generating means and the shaping member along the axis for selectively deflecting the electron beam to illuminate at least a selected portion of the shaping member, a reference deflection means positioned intermediate the shaping member and the target for referencing the electron beam to axis, convergence means positioned intermediate the shaping member and the reference deflection means for substantially simultaneously converging and focusing the electron beam, and, an electron focusing lens positioned intermediate the reference deflection means and the target, said focusing lens being adapted to cause independent focus conditions upon the shaped beam adjacent the target.

2. In a shaped beam tube including beam generating and projecting means capable of causing an electron beam projected generally along tube axis to be impinged upon a target, beam shaping means transversely disposed in the path of the beam for selectively shaping the beam, selection deflection means and reference deflection means for directing the beam upon the shaping means and referencing the beam to the axis, respectively, the improvement comprising a convergence means disposed intermediate the selection and reference deflection means capable of imaging the shaping means adjacent the target, and an independently controllable electron focusing lens intermediate the reference deflection means and the target for imaging the beam at the target, the focusing lens being adapted to selectively cause focus conditions upon the beam adjacent the target independently of convergence means.

3. In a shaped beam tube including beam generating and projecting means capable of causing an electron beam projected generally along tube axis to be impinged upon a target, beam shaping means transversely disposed in the path of the beam for selectively shaping the beam, selection deflection means and reference deflection means for directing the beam upon the shaping means and referencing the beam to the axis, respectively, the improvement comprising a convergence means disposed intermediate the selection and reference deflection means capable of establishing predetermined imaging and size conditions upon the shaped beam, and an independently controllable electron focusing lens intermediate the reference deflection means and the target for controlling the shaped beam, the focusing lens being capable of effecting, independently of the convergence means, imaging and size conditions upon the shaped beam altering said predetermined imaging and size conditions.

4. In a shaped beam tube including beam generating and projecting means capable of causing an electron beam projected generally along tube axis to be impinged upon a target, beam shaping means transversely disposed in the path of the beam for selectively shaping the beam, selection deflection means and reference deflection means for directing the beam upon the shaping means and referencing the beam to the axis, respectively, the improvement comprising a convergence means disposed intermediate the selection and reference deflection means capable of establishing predetermined imaging and size conditions upon the shaped beam, and an electrostatic electron focusing leans intermediate the reference deflection means and the target for controlling the shaped beam, the focusing lens being capable of effecting, independently of the convergence means, imaging and size conditions upon the shaped beam altering said predetermined imaging and size conditions.

5. In a shaped beam tube including beam generating and projecting means capable of causing an electron beam projected generally along tube axis to be impinged upon a target, beam shaping means transversely disposed in the path of the beam for selectively shaping the beam, selection deflection means and reference deflection means means, imaging and size conditions upon the shaped beam altering said predetermined imaging and size conditions.

References Cited in the le of this patent UNITED STATES PATENTS 2,276,359 Von Ardenne Mar. 17, 1942 2,532,339 Schlesinger Dec. 5, 1950 2,696,571 Law Dec. 7, 1954 2,728,872 Smith Dec. 27, 1955 2,769,116 Koda et al. Oct. 30, 1956 

1. IN A SHAPED BEAM TUBE INCLUDING BEAM GENERATING AND PROJECTING MEANS AT ONE END THEREOF FOR PROJECTING AN ELECTRON BEAM ALONG A TUBE AXIS, AND A TARGET RESPONSIVE TO SAID BEAM AT THE OTHER END THEREOF, A BEAM SHAPING MEMBER POSITIONED ALONG THE AXIS INTERMEDIATE THE TARGET AND THE BEAM GENERATING MEANS FOR SELECTIVELY SHAPING THE ELECTRON BEAM, A SELECTION DEFLECTION MEANS POSITIONED INTERMEDIATE THE GENERATING MEANS AND THE SHAPING MEMBER ALONG THE AXIS FOR SELECTIVELY DEFLECTING THE ELECTRON BEAM TO ILLUMINATE AT LEAST A SELECTED PORTION OF THE SHAPING MEMBER, A REFERENCE DEFLECTION MEANS POSITIONED INTERMEDIATE THE SHAPING MEMBER AND THE TARGET FOR REFERENCING THE ELECTRON BEAM TO AXIS, CONVERGENCE MEANS POSITIONED INTERMEDIATE THE SHAPING MEM- 